1. Field of the Invention
The present invention relates to a welding-wire-storing pail pack in which a coil of welding wire is stored such that the axis thereof extends vertically, a container intended for the welding-wire-storing pail pack, and a pressing member intended for the welding-wire-storing pail pack and to be placed on the coil of welding wire, and more particularly to a welding-wire-storing pail pack in which welding wire is prevented from coming off the coil while being pulled out, a container for the pail pack, and a pressing member for the pail pack.
2. Description of the Related Art
A cylindrical container that stores welding wire dropped thereinto in such a manner as to make loops is referred to as a pail pack container. A pail pack container stores a large volume of welding wire and is used when the welding wire is transported to the user. In general, welding wire stored in a pail pack container weighs as heavy as 200 to 500 kg.
The welding wire is decoiled in such a manner as to be pulled upward from the coil of the welding wire wound in such a manner as to make loops. Therefore, to prevent the decoiled portion of the wire from being twisted, the welding wire is dropped into a pail pack container in such a manner as to be twisted in a direction opposite to the direction of the twist occurring when the wire is decoiled. To prevent the wire twisted in such a manner from jumping while being decoiled, an annular pressing plate is placed on the top of the coil of the welding wire. That is, the jumping of the wire is prevented under the weight of the pressing plate applied to the coil of the wire from above.
FIGS. 4A and 4B are a schematic perspective view and a vertical cross-sectional view, respectively, of a known welding-wire-storing pail pack. As shown in FIGS. 4A and 4B, a coil 30 of welding wire 3 is placed in a pail pack container 2 by windingly dropping the welding wire 3 into the pail pack container 2. An inner shell 2a extends on the inner side of the coil 30. An annular pressing plate 10 is placed on the coil 30. The coil 30 is pressed from above under the weight of the pressing plate 10, whereby the welding wire 3 is prevented from jumping. When the welding wire 3 is used, the welding wire 3 is pulled out of the gap between the inner shell 2a and the pressing plate 10.
When the welding wire 3 is decoiled from the coil 30, the welding wire 3 may be tangled or kinked. To prevent the tangling and kinking of the decoiled portion of the welding wire 3, pressing plates of various configurations have been proposed. For example, Japanese Unexamined Patent Application Publication No. 2005-169468 discloses a pail pack container in which the outer shell is secured at the bottom end thereof to the bottom plate by caulking, and a pressing plate includes a lower portion whose outer diameter is smaller than the inner diameter of the caulked portion and an upper portion whose outer diameter is larger than the inner diameter of the caulked portion but is smaller than the inner diameter of a portion other than the caulked portion. Thus, the pressing plate is prevented from being caught by the caulked portion while the welding wire is being decoiled, and the welding wire is decoiled to the bottommost turn without being tangled and kinked.
Japanese Unexamined Patent Application Publications No. 2007-029971 and No. 2007-000927 each disclose a technique in which the pressing plate includes a flat portion and a barrier portion provided on the outer periphery of the flat portion and extending upward, whereby welding wire is prevented from coming out of the gap between the pressing plate and the outer shell, and disturbance of the coil is thus prevented.
Welding wire is decoiled such that the wire is pulled out of the gap between the pressing plate and the inner shell. Therefore, in a welding-wire-storing pail pack such as those disclosed in Japanese Unexamined Patent Application Publications No. 2005-169468, No. 2007-029971, and No. 2007-000927 in which the wire is coiled up to a position in close proximity to the outer periphery of the inner shell, a decoiled portion of the wire may be bound around the inner shell, causing decoiling failure. Therefore, as shown in FIG. 5, a gap of a specific size is provided between the coil 30 and the inner shell 2a, whereby decoiling failure due to such wire binding is prevented. Nevertheless, the welding wire 3 wound into the coil 30 may slip off (come off) into the gap between the coil 30 and the inner shell 2a when the welding wire 3 is being decoiled. The come-off of the wire occurs because of repeated twisting of the wire occurring when the wire is decoiled or the interference between the decoiled portion of the wire and the wound portion of the wire below the decoiled portion. As described above, when welding wire is dropped into a pail pack container, the wire is twisted in a direction opposite to the direction of the twist occurring when the wire is decoiled. Therefore, as shown in FIG. 6A, the welding wire that has come off may move circularly because of the twist and may rise over the inner shell 2a. As the welding wire 3 continues to be decoiled, referring now to FIG. 6B, the wire may be bent, i.e., kinked, resulting in decoiling failure. If the wire is kinked, welding work needs to be suspended and, after the wire is cut at the kinked portion, to be started again. This may reduce the efficiency of welding work. If the pail pack is replaced so as to restart the welding work, the welding wire in the pail pack that has been kinked is wasted.
Even in the case where a gap of a specific size is provided between the coil and the inner shell, if the welding wire slips off, referring now to FIG. 7A, the welding wire 3 that has been excessively decoiled from the coil 30 may run around the inner shell 2a and is tightly bound around the inner shell 2a as shown in FIG. 7B, resulting in decoiling failure.
An exemplary technique of preventing the occurrence of welding-wire-decoiling failure is disclosed in Japanese Unexamined Patent Application Publication No. 2003-238030. FIG. 8 schematically shows the known technique of preventing the occurrence of welding-wire-decoiling failure. As shown in FIG. 8, in the technique disclosed in Japanese Unexamined Patent Application Publication No. 2003-238030, the outer diameter of the inner shell 2a provided on the inner side of the coil 30 is small, whereas the width of the pressing plate 10 is significantly extended toward the inner shell 2a, whereby the weight of the pressing plate 10 applied to the inner portion of the coil 30 is made larger than that applied to the outer portion of the coil 30. Thus, the welding wire 3 is prevented from slipping off.
Even with such a pressing plate 10, the come-off of the welding wire 3 into the gap between the inner shell 2a and the coil 30 cannot be prevented sufficiently. Consequently, decoiling failure due to the occurrence of kink and the welding wire bound around the inner shell cannot be prevented.